 Fibromyalgia is one of the most common joint and muscle diseases, afflicting millions of Americans, characterized by widespread musculoskeletal pain and often accompanied by other symptoms such as fatigue. The medical profession used to think it was all in people's heads, but today there's irrefutable evidence that it is indeed a disorder of the body and not just the mind. Back in 2003, an influential paper was published out of the Mayo Clinic in which a shocking 93% of fibromyalgia-type patients were found to be vitamin D deficient, and so they concluded that all such patients are at high risk of severe vitamin D deficiency. But wait a second, said the skeptics. There was no control group. Where's the Mayo Clinic located? Minnesota, maybe 90% of everyone in Minnesota, is D deficient. When controlled studies were done, some did indeed find that those suffering from these kind of pain syndromes were significantly more likely to be D deficient, but other studies did not. Even if all the studies did, though, that doesn't mean that low vitamin D levels cause fibromyalgia. Maybe chronic widespread pain disorders like fibromyalgia cause low vitamin D. It's the sunshine vitamin after all, and fibromyalgia patients may not be running around outside as much as healthy controls. To know if vitamin D is contributing to the disease, you have to put it to the test. Studies like these found that the majority of those with pain syndromes and low D levels appeared to benefit from vitamin D supplementation, and clinical improvement in up to 90% of patients. You can imagine how rife vitamin D deficiency is among Arab women in the Middle East. But these studies weren't controlled either. Maybe they would have gotten better on their own without the supplement, or maybe it was the placebo effect. There are many examples in the medical literature of treatments that looked great in uncontrolled trials, like hyperbaric oxygen therapy for multiple sclerosis, but when put to the test in randomized controlled trials, they failed miserably. And that's what seemed to happen in the first randomized controlled trial of vitamin D for a fibromyalgia type syndrome in 2008. No significant difference in pain scores, though the study only lasted three months, and in that time researchers were only able to get vitamin D blood levels up to about 30. Unfortunately no controlled study had ever been done pushing levels any higher until 2014. Fibromyalgia patients were given up to 2400 units of D a day for 20 weeks, and so their D levels rose up to like 50. And then once they stopped the vitamin D, levels came back down to match the placebo. And that was reflected in their pain scores, a significant drop in pain severity while they were on the D, and then back to baseline when they were off of it. The researchers concluded that this economical, in fact over-the-counter therapy, with a low side effect profile may well be considered in patients with fibromyalgia syndrome.